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//! Implementation of GraphWalk for DropRanges so we can visualize the control
//! flow graph when needed for debugging.
use rustc_graphviz as dot;
use rustc_hir::{Expr, ExprKind, Node};
use rustc_middle::ty::TyCtxt;
use super::{DropRangesBuilder, PostOrderId};
/// Writes the CFG for DropRangesBuilder to a .dot file for visualization.
///
/// It is not normally called, but is kept around to easily add debugging
/// code when needed.
pub(super) fn write_graph_to_file(
drop_ranges: &DropRangesBuilder,
filename: &str,
tcx: TyCtxt<'_>,
) {
dot::render(
&DropRangesGraph { drop_ranges, tcx },
&mut std::fs::File::create(filename).unwrap(),
)
.unwrap();
}
struct DropRangesGraph<'a, 'tcx> {
drop_ranges: &'a DropRangesBuilder,
tcx: TyCtxt<'tcx>,
}
impl<'a> dot::GraphWalk<'a> for DropRangesGraph<'_, '_> {
type Node = PostOrderId;
type Edge = (PostOrderId, PostOrderId);
fn nodes(&'a self) -> dot::Nodes<'a, Self::Node> {
self.drop_ranges.nodes.iter_enumerated().map(|(i, _)| i).collect()
}
fn edges(&'a self) -> dot::Edges<'a, Self::Edge> {
self.drop_ranges
.nodes
.iter_enumerated()
.flat_map(|(i, node)| {
if node.successors.len() == 0 {
vec![(i, i + 1)]
} else {
node.successors.iter().map(move |&s| (i, s)).collect()
}
})
.collect()
}
fn source(&'a self, edge: &Self::Edge) -> Self::Node {
edge.0
}
fn target(&'a self, edge: &Self::Edge) -> Self::Node {
edge.1
}
}
impl<'a> dot::Labeller<'a> for DropRangesGraph<'_, '_> {
type Node = PostOrderId;
type Edge = (PostOrderId, PostOrderId);
fn graph_id(&'a self) -> dot::Id<'a> {
dot::Id::new("drop_ranges").unwrap()
}
fn node_id(&'a self, n: &Self::Node) -> dot::Id<'a> {
dot::Id::new(format!("id{}", n.index())).unwrap()
}
fn node_label(&'a self, n: &Self::Node) -> dot::LabelText<'a> {
dot::LabelText::LabelStr(
format!(
"{n:?}: {}",
self.drop_ranges
.post_order_map
.iter()
.find(|(_hir_id, &post_order_id)| post_order_id == *n)
.map_or("<unknown>".into(), |(hir_id, _)| format!(
"{}{}",
self.tcx.hir().node_to_string(*hir_id),
match self.tcx.hir().find(*hir_id) {
Some(Node::Expr(Expr { kind: ExprKind::Yield(..), .. })) => " (yield)",
_ => "",
}
))
)
.into(),
)
}
}
|